Vapor deposition apparatus, vapor deposition method, and method for manufacturing organic EL display apparatus

ABSTRACT

A vapor deposition method and a vapor deposition apparatus that, when a vapor deposition material is deposited on a substrate, make it possible to form deposition layer pattern precisely so that the deposition layer pattern is formed uniformly without a gap formed between a deposition mask and the substrate. A deposition mask is disposed with its periphery held by a frame. A substrate on which a vapor deposition layer is to be formed is mounted over an upper surface of the deposition mask. A vapor deposition source is disposed facing the deposition mask and evaporates a vapor deposition material. The vapor deposition is performed while the substrate is pressed vertically at a position of a center of deflection of the deposition mask and on an upper surface of the substrate until that a length of the substrate substantially becomes identical to a length of the deposition mask being bowed down and expanded.

TECHNICAL FIELD

The present invention relates to a vapor deposition apparatus, a vapordeposition method, for example, which are used to deposit organic layersof the organic EL display apparatus, and a method for manufacturing anorganic electro-luminescence (EL) display apparatus. More specifically,the present invention relates to a vapor deposition apparatus and avapor deposition method that make it possible to reduce unsharpness andnon-uniformity of vapor deposition patterns by performing vapordeposition while the substrate for vapor deposition is in contact with adeposition mask, and also relates to a method for manufacturing anorganic EL display device with this vapor deposition method.

BACKGROUND ART

Contemporary display apparatus such as organic EL display apparatus needto employ high definition design, and deposition masks used thereforhave fine opening portions. As a deposition mask, a resin film that canbe processed precisely or a complex mask which includes a resin film anda metal support layer trends to be used. Due to enlargement of screen oforganic EL display apparatus or boost their production in which aplurality of panels are deposited at one time, that is multiple-panelmasks, the deposition mask trends to be enlarged. As a result, somedeposition masks have a size of as large as one meter or more per side.

When an organic EL display apparatus is manufactured, for example, amask 81 and a substrate 83 are placed inside a chamber 90 as illustratedin FIG. 6. Further, the mask 81 is mounted on a mask support base 85,and the substrate 83 is mounted on the mask 81. When from a vapordeposition source 84 disposed under the mask 81 a vapor depositionmaterial evaporates, this vapor deposition material passes throughopenings of the mask 81 and is deposited on the substrate 83. In thisway, a deposition layer of organic layers is formed on the substrate 83(e.g., see Patent Document 1). In FIG. 6, the reference numeral 82denotes a frame used to fix a periphery of the mask 81, and thereference numeral 86 denotes a substrate support base used to hold thesubstrate 83.

As the substrate 83 and the mask 81 become larger in size, the mask 81is more prone to being bowed down downward at its center during thevapor deposition process, which leads to a formation of defectivepattern layers on the substrate 83. Patent Document 1 describesprovision of a substrate-mask contact unit 88. In this description, aflexible plate 87 of the substrate-mask contact unit 88 applies pressureto an entire bowed surface of the substrate 83 toward the mask 81,thereby bringing the substrate 83 into contact with the mask 81.

Patent Document 2 discloses provision of a substrate pressing unit 91.The substrate pressing unit 91 applies loads on the back surface of thesubstrate 83 at a plurality of points in accordance with an amount ofthe deflection of the substrate 83, thereby improving the contactbetween the substrate 83 and the mask 81. This enables a vapordeposition pattern to be formed precisely on the substrate 83 even whenthe substrate 83 and the mask 81 are enlarged. More specifically, inthis description, as illustrated in FIG. 7, the pressing unit 91 formedby screwing a plurality of plungers 91 b into through-holes in theplunger holder 91 a applies the loads on the substrate 83 at theplurality of points, thereby bringing the substrate 83 into contact withthe mask 81.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: JP 2009-277655 A

Patent Document 2: JP 2005-281746 A

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

The above flexible plate described in Patent Document 1 is not deemed tobe high in rigidness. Therefore, Patent Document 1 may lack an intentionto deform the substrate for vapor deposition into a certain shape byapplying the loads on the substrate for vapor deposition via theflexible plate that conforms to the shape of the substrate for vapordeposition. Furthermore, it may be difficult to effectively apply theloads on the substrate for vapor deposition by applying the loads on theflexible plate supported at specific points. Moreover, the deformedshape of the substrate for vapor deposition, namely, the deformed shapeof the flexible plate may be unpredictable. Also, a method for bringingthe substrate for vapor deposition into contact with the deposition maskmay be unclear. Moreover, it may be unclear how to apply loads on theflexible plate in order to bring the substrate for vapor deposition intocontact with the deposition mask, especially when the substrate forvapor deposition is made of glass. In short, Patent Document 1 fails todisclose or suggest a method for bringing the substrate for vapordeposition into contact with the deposition mask. More specifically, itneither discloses nor suggests what kind of object is used to press thesubstrate for vapor deposition, what shape this object has, and howstrong the object needs to press the substrate for vapor deposition.

In Patent Document 2, the plurality of plungers apply the loads on thesubstrate for vapor deposition at the plurality of points. However, thepoints at which the loads are applied on the substrate for vapordeposition may be unclear. Further, it may also be unclear how many andwhere the points are and how heavy each load is. When the loads areapplied on the plurality of points, the deflection of the substrate forvapor deposition can depend on the relative positional relationship ofthe plungers.

An object of the present invention, which has been made in the view ofthe above situations, is to provide a vapor deposition method and avapor deposition apparatus that, when a vapor deposition material isdeposited on a substrate for vapor deposition, make it possible to forma deposition pattern precisely so that the deposition pattern is notformed non-uniformly due to a gap formed between a deposition mask andthe substrate for vapor deposition.

Another object of the present invention is to provide a method formanufacturing an organic EL display apparatus of a high display qualityby using the above vapor deposition method.

Means to Solve the Problem

With increasing definition of organic EL and other display apparatuses,as described above, a resin film tend to increasingly used in adeposition mask, and a substrate for vapor depositions and thedeposition masks have been increasingly enlarged. On the other hand, aproblem that the deposition mask is bowed downward at a center isbecoming more prominent. In some cases, a magnetic chuck method isemployed. In this magnetic chuck method, a complex deposition mask inwhich a metal support layer made of a magnetic material is laminated ona resin film is used, and a magnet is provided on an opposite side of asubstrate for vapor deposition to the deposition mask and attracts thedeposition mask. To form a fine pattern, however, a thinner metalsupport layer needs to be used in order to prevent a shadow from beingcaused during vapor deposition. In this case, a magnetic attractiveforce generated by the magnet, which is proportional to a volume of itsmagnetic material, is weakened. Even if a magnet that can generate astrong magnetic field is used, the deposition mask may be deformed orwrinkled, because the deposition mask has a small thickness and thus lowrigidness. If the magnet generates an excessively strong, attractiveforce, the deposition mask may damage the vapor-deposited surface of thesubstrate for vapor deposition, which can be a problem. Therefore, themethod for attracting the deposition mask strongly with a magnetic forcemay be improper to the solution.

The method for applying pressure to a substrate for vapor deposition viaa flexible plate or other sheet object, as described in Patent Document1, or the method for applying loads on the substrate for vapordeposition at a plurality of points via plungers, as described in PatentDocument 2, may have difficulty bringing the substrate for vapordeposition into contact with the deposition mask, because points atwhich loads are applied effectively on the substrate for vapordeposition are unclear, as described above. If a gap is created betweenthe substrate for vapor deposition and the deposition mask, a pattern ofopenings in the deposition mask may not be transferred correctly to thesubstrate for vapor deposition. As an example, an area of the substratefor vapor deposition on which the vapor deposition material is depositedto form a pattern of openings may be larger than the pattern of openingsin the deposition mask. As another example, the boundary betweenopenings in the vapor deposition material may be unsharped. As a result,patterns each made of a deposition layer of organic layers are notformed uniformly on the substrate for vapor depositions. If suchdeposition layer is used for pixels of a display apparatus, this displayapparatus may exhibit a low display quality, which can be a problem.

The present inventor et al. have diligently studied a method forsuppressing unsharpness or non-uniformity of deposited patterns byperforming vapor deposition while a deposition mask and a substrate forvapor deposition are in substantial contact with each other with littlegap therebetween. As a result of this study, it was found that it ispossible to perform vapor deposition while a substrate for vapordeposition and a deposition mask are in substantial contact with eachother throughout the vapor deposition, by mounting the substrate forvapor deposition on an upper surface of the deposition mask and bypressing down vertically the substrate for vapor deposition at aposition of the center of deflection (where the deposition mask isdisplaced maximally from its flat state) of the deposition mask and atan upper surface (surface on an opposite side to the deposition mask) ofthe substrate for vapor deposition until the substrate for vapordeposition and the deposition mask are bowed down to substantially thesame degree. In this case, if the substrate for vapor deposition is asubstrate having high rigidness such as a thick glass plate, when thesubstrate for vapor deposition is pressed locally at its center, it iseasily curved to make contact with the deposition mask. However, if thesubstrate for vapor deposition is a thin glass plate or a flexiblesubstrate, it may not be curved from the center of the deflection towardthe fulcrum on the periphery. In this case, it is preferred that apressing tool used to press the substrate for vapor deposition is formedsuch that at least a portion to be contact with the substrate for vapordeposition is formed into an arched shape whose radius of curvature isidentical to that of the center of the substrate for vapor depositionbeing pressed. By this way, the substantially entire surfaces of thesubstrate for vapor deposition and the deposition mask can be broughtinto contact with each other. This is because the bowed surface of thedeposition mask can be regarded as a substantially spherical surface.

The amount of deflection of the deposition mask is preferably the sum ofa deflection length of the deposition mask arched at a fulcrum on itsperiphery and an amount of the expansion of the deposition mask causedby temperature rise during the vapor deposition. That is, on the basisof the length of the bowed deposition mask which includes its thermalexpansion, an amount in which the substrate for vapor deposition ispressed and a radius of curvature of a spherical surface of the pressingtool that makes contact with the substrate for vapor deposition aredetermined. The above pressed amount and the radius of curvature aredetermined in the following manner. First, a cross section of thedeposition mask which is taken along a line that is parallel to its oneside and that passes through the center of the deflection of thedeposition mask is obtained. Then, the curved line of the cross sectionobtained is regarded as an isosceles triangle, a peak of whichcorresponds to the center of the deflection and a base of whichcorresponds to a line segment between fulcra at both ends of thedeposition mask. By using the length of the base of the isoscelestriangle and the length (maximum amount of deflection) of a verticalline extending from the peak to the base, the entire length of the boweddeposition mask can be approximately expressed as the total length ofthe two equal sides of the isosceles triangle. More specifically, thebowed deposition mask is defined as two right triangles, which areobtained by equally dividing the above isosceles triangle along avertical line passing through the center of the deflection of thedeposition mask. Using a half (L₀/2) of a base length L₀ (a length ofthe deposition mask when it is not bowed down) and the maximum amount ofdeflection d₀, the length [(L₀/2)²+d₀ ²]^(1/2) of the hypotenuse of oneof the right triangles is calculated. The entire length of the boweddeposition mask is approximately expressed as twice the length of thehypotenuse of this right triangle. Details of this will be describedlater.

As a result of another diligent study, the present inventor et al. havefound that, if a plurality of active regions in each of which a patternof opening portions is to be formed are present on the deposition mask,the entire deposition mask is bowed down at the fulcrum on itsperiphery, and moreover, the active regions are individually bowed down(see the exaggerated diagram in FIG. 4A). In addition, it has been foundthat it is necessary to expand the deposition mask by further pressingthe substrate for vapor deposition, in consideration of the deflectionof the individual active regions. In this case, the deflection of anumber (n portions) of active regions may be considered at one time bypressing the deposition mask at its center. Alternatively, loads may beapplied on the respective active regions at their centers; the load oneach active region is determined by the sum of its amount of deflectionand the amount of deflection of the entire deposition mask at itsposition. Details of this will be described later too.

A vapor deposition method of the present invention comprising:

disposing a deposition mask in a horizontal position with holding itsperiphery; mounting a substrate for vapor deposition over an uppersurface of the deposition mask so as to be overlaid on the depositionmask, a vapor deposition layer to be formed on the substrate for vapordeposition; disposing a vapor deposition source so as to face thedeposition mask; and forming the vapor deposition layer on the substratefor vapor deposition by deposing a vapor deposition material in thevapor deposition source; wherein the substrate for vapor deposition ispressed vertically at a position of a center of deflection of thedeposition mask and that is on an upper surface of the substrate forvapor deposition, by an amount equating to or exceeding a depth of thedeflection of the deposition mask relative to a fulcrum on the peripheryof the deposition mask, and a vapor depositing is performed while thesubstrate for vapor deposition is in contact with the deposition mask.

A vapor deposition apparatus of the present invention comprising: a maskholder on which a deposition mask is mounted; a substrate holderprovided so as to be able to hold a substrate for vapor deposition; atouch plate provided above the substrate for vapor deposition held bythe substrate holder, the touch plate being in contact with thesubstrate for vapor deposition; a vapor deposition source thatevaporates or sublimates a vapor deposition material, the vapordeposition source being provided on an opposite side of the depositionmask to the substrate holder, the deposition mask being mounted on themask holder; and a pressing device that presses an upper surface of thesubstrate for vapor deposition, wherein the pressing device is providedso as to be able to press vertically the substrate for vapor depositionat a center position of deflection of the deposition mask on the uppersurface of the substrate for vapor deposition held by the substrateholder.

A method, of the present invention, for manufacturing an organic ELdisplay apparatus by depositing organic layers on a device substratecomprising: forming the device substrate by forming at least a TFT and afirst electrode on a support substrate; forming a deposition layer ofthe organic layers on the device substrate by depositing organicmaterials over the first electrode with the above vapor depositionmethod; and forming a second electrode on the deposition layer.

EFFECTS OF THE INVENTION

According to the vapor deposition method of the present invention, theupper surface of the substrate for vapor deposition is pressed along acentral line of the deflection of the deposition mask. In this case, thepressed point can be positioned at the maximum deflection point. Thus,the pressed force is concentrated on the substrate for vapor deposition,thereby easily pressing the substrate for vapor deposition by apredetermined amount. As a result, the substrate for vapor depositioncan easily be pressed by the predetermined amount even if the substratefor vapor deposition is a glass plate. When the substrate for vapordeposition made of glass is pressed at a single point, it is notdepressed locally at this point but curved smoothly across the wholebody, because glass has high rigidness. In other words, when thesubstrate for vapor deposition is pressed only at its center, it isdepressed into an incurved shape with the center being its peak. As aresult, the pressed force effectively acts on the substrate for vapordeposition and provides the incurved surface similar to the deflectionof the deposition mask, thereby improving the contact between thesubstrate for vapor deposition and the deposition mask. If the substratefor vapor deposition is a thin glass plate, a flexible substrate made ofa resin film, or other substrate having low rigidness, a surface of thepressing tool which abuts against the substrate for vapor depositionneeds to be formed into a curved shape whose radius of curvature isidentical to that of the deposition mask in a bowed state. In this case,a force mainly acts on the center of the deflection of the substrate forvapor deposition, but also acts on its surround area so that it isdeformed in conformity with the shape of the pressing tool. It should benoted that a bar of the pressing tool pressing against the substrate forvapor deposition has preferably an end with a curved surface rather thana sharp or flat end, even if the substrate for vapor deposition is aglass plate having high rigidness. The curved surface of the end ispreferably similar to that of the deflection of the deposition mask.

According to the vapor deposition apparatus of the present invention,the pressing device is provided so as to be able to press vertically thesubstrate for vapor deposition at the position of the center of thedeflection of the deposition mask and on the upper surface of thesubstrate for vapor deposition held by the substrate holder. Therefore,the pressing device can easily press the substrate for vapor depositionby a predetermined amount. As an example, in the pressing device, anactuator may press a plunger (preferably has an end with a curvedsurface as described above) by the predetermined amount. As anotherexample, a pressing tool that is formed of a member having apredetermined size of curved surface such as a sphere or the like, orthat has a wide, spherical surface that abuts against the substrate forvapor deposition may be disposed at a predetermined position between thetouch plate and the substrate for vapor deposition held by the substrateholder. And, the actuator may press down the touch plate verticallyagainst this pressing tool. This configuration can easily press down thesubstrate for vapor deposition by the predetermined amount.

According to the method for manufacturing the organic EL displayapparatus of the present invention, it is possible to provide very sharppixels without forming unsharped deposition layers of organic layershaving a non-uniform size. Consequently, it is possible to provide anorganic EL display apparatus of a high display quality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram illustrating an embodiment of a vapordeposition apparatus of the present invention.

FIG. 1B is a schematic diagram illustrating a modification of thepressing tool in the vapor deposition apparatus in FIG. 1A.

FIG. 2A is an explanatory diagram illustrating deflection of thedeposition mask in FIGS. 1A and 1B.

FIG. 2B is an explanatory diagram illustrating a method for determininga length of the deposition mask in FIGS. 1A and 1B when it is boweddown.

FIG. 2C is an explanatory diagram illustrating a method for determininga radius of curvature of the deposition mask in FIG. 2A when it is boweddown.

FIG. 3A is an explanatory plan diagram illustrating the deposition maskwhen a plurality of regions (active regions) each in which openings areformed are present in the deposition mask (explanatory plan diagram fromwhich a substrate for vapor deposition in FIG. 3B is removed).

FIG. 3B is an explanatory diagram illustrating deflection in activeregions in FIG. 3A.

FIG. 3C is an explanatory diagram illustrating a method forapproximately determining a length of each active region in FIG. 3B.

FIG. 3D is an explanatory diagram illustrating an embodiment of a methodfor bringing the substrate for vapor deposition into contact with thedeposition mask, in the case of FIG. 3A.

FIG. 3E is an explanatory diagram illustrating an example of a methodfor calculating a pressed amount in FIG. 3D.

FIG. 4A is an explanatory diagram illustrating another embodiment of amethod for bringing the substrate for vapor deposition into contact withthe deposition mask, in the case of FIG. 3A.

FIG. 4B is a schematic diagram illustrating an example of a method forcalculating a pressed amount in FIG. 4A.

FIG. 4C is a diagram illustrating an example of a shape of a widepressing tool for use in bringing the substrate for vapor depositioninto contact with the deposition mask, in the case of FIG. 4A.

FIG. 5A is an explanatory diagram illustrating a vapor depositionprocess in a method for manufacturing an organic EL display apparatus ofthe present invention.

FIG. 5B is an explanatory diagram illustrating a process in whichorganic layers are deposited with the method for manufacturing theorganic EL display apparatus of the present invention.

FIG. 6 is a diagram illustrating an example of a conventional process inwhich the substrate for vapor deposition is brought into contact with adeposition mask when a vapor deposition material is vapor-deposited on asubstrate for vapor deposition.

FIG. 7 is a diagram illustrating another example of a conventionalprocess in which the substrate for vapor deposition is brought intocontact with the deposition mask.

EMBODIMENT FOR CARRYING OUT THE INVENTION

With reference to the accompanying drawings, a description will be givenof an embodiment of a vapor deposition method and a vapor depositionapparatus of the present invention. In the vapor deposition method ofthe present invention, a deposition mask 1 is disposed in a horizontalposition with its periphery held by a frame 12. Mounted on the uppersurface (in a vertical direction) of the deposition mask 1 is asubstrate 2 for vapor deposition on which a vapor deposition layer is tobe formed. The deposition mask 1 and the substrate 2 for vapordeposition are overlaid on each other. Disposed under the depositionmask 1 is a vapor deposition source 5 that vaporizes a vapor depositionmaterial 51 to form the vapor deposition layer on the substrate 2 forvapor deposition. This embodiment is characterized in that: thesubstrate 2 for vapor deposition is pressed vertically at a position ofa center of deflection of the deposition mask 1 and on an upper surfaceof the substrate 2 for vapor deposition by an amount equating to orexceeding a depth of the deflection of the deposition mask 1 relative toa fulcrum on its periphery; and then vapor deposition is performed whilethe substrate 2 for vapor deposition and the deposition mask 1 are incontact with each other.

More specifically, the substrate 2 for vapor deposition is pressed untila length of an arc between a point on a side of the deposition mask 1 atwhich the substrate 2 for vapor deposition is in contact with thefulcrum and a point on the surface on a side of the deposition mask 1 atwhich the substrate 2 for vapor deposition intersects a vertical line tothe center of the deflection becomes substantially identical to a lengthof an arc between the fulcrum (point B in FIG. 2A) on the periphery ofthe deposition mask 1 and a center (point A in FIG. 2A) of thedeflection of the deposition mask 1. In other words, the substrate 2 forvapor deposition is pressed until surfaces of the deposition mask 1 andthe substrate 2 for vapor deposition which are in contact with eachother have substantially the same radius of curvature. The “pressed byan amount equating to or exceeding the depth of the deflection of thedeposition mask 1” needs to be done in order to compensate for thefollowing deflection of the deposition mask 1: the deflection of thedeposition mask 1 at the fulcrum on the periphery; deflection of eachactive region 14 (see FIGS. 3A and 3B) that will be described later; anddeflection of the deposition mask caused by thermal expansion during thevapor deposition. The expression “compensate for the thermal expansion”means that the deposition mask 1 has been expanded in advance by anamount corresponding to the thermal expansion, and thus the size of thedeposition mask 1 remains unchanged from the state of being expanded inadvance even when the deposition mask 1 is thermally expanded. In thecase of this embodiment, the thermal expansion is compensated for,because the deposition mask 1 is expanded by being pressed. There arecases where an actual pressed amount is about twice or more to ten timesor less, more preferably, about third times or more to seven times orless the amount of deflection relative to the fulcrum on the periphery.In short, the substrate 2 for vapor deposition is preferably pressed byan amount exceeding the depth of the deflection relative to the fulcrumon the periphery. Furthermore, pressing the substrate 2 for vapordeposition by an amount exceeding the total amount of deflection of thedeposition mask 1 or more is also effective in bringing the substrate 2for vapor deposition into contact with the deposition mask 1. It shouldbe noted that the arrow line above the substrate 2 for vapor depositionin FIG. 3B denotes a position at which a load is applied on thesubstrate 2 for vapor deposition in order to press the substrate 2 forvapor deposition.

FIG. 1A illustrates an example in which a pressing device 3 presses apressing tool 30, which is a sphere 31 such as a steel ball or a plasticball having high rigidness, against the substrate 2 for vapor depositionby using a touch plate 41 and an unillustrated pressing member includingan actuator. However, the pressing device 3 is not limited to thisexample. Alternatively, the pressing device 3 may press a plunger by acertain amount by using the actuator or other similar member. In thiscase, it is preferable that the plunger have a curved shape at its end.It is more preferable that the end of the plunger have a sphericalsurface whose radius of curvature is identical to that of a curvedsurface of the deposition mask 1. The pressing tool 30 does notnecessarily have to be the sphere 31 and may have any other shapeaccordingly. As illustrated in FIG. 1B, for example, the pressing tool30 may be a spherical cap 32 formed by partly cutting off a sphere. Inother words, a surface of the pressing tool 30 which abuts against thesubstrate 2 for vapor deposition is formed into a spherical shape whoseradius of curvature is identical to that of the curved surface of thedeposition mask 1. If the pressing tool 30 has a shape as describedabove, it mainly presses the center of the deflection. However, thepressing force also acts on its surrounding area, thereby making itpossible to press the substrate 2 for vapor deposition while forming thesurface of the substrate 2 for vapor deposition into a spherical shape.In this case, the substrate 2 for vapor deposition is pressed in amanner similar to the way in which it is pressed locally. The forceacting on the area around the center is auxiliary. Even when the forcethat would press the center is simply distributed across this area, itstotal amount is not changed. As illustrated in FIG. 4C, the pressingtool 30 may be a spherical cap 33 with projection, in which someprojections are formed on a spherical cap. A width of the sphericalsurface (a length of a portion of the spherical cap which engages withthe touch plate 41 in FIG. 1B) is not specifically limited, and thelength may have any width within an inside size of the frame.

To allow the pressing tool 30 to engage with the touch plate 41, a basesection 32 a is formed in the spherical cap 32 as illustrated in FIG.1B, or a base section 33 a is formed in the spherical cap 33 asillustrated in FIG. 4C. However, the base sections 32 a and 33 a may beoptional. Alternatively, the spherical cap 32 with no base section 32 aor the spherical cap 33 with no base section 33 a may be bonded to thetouch plate 41. The spherical cap 32 with no base section 32 a or thespherical cap 33 with no base section 33 a may be integrated with thetouch plate 41 or any other member. The spherical surface of the portionof the pressing tool 30 which abuts against the substrate 2 for vapordeposition has a radius of curvature which is identical to that of thecurved surface of the deflection of the deposition mask 1, morespecifically, that of a portion of the deposition mask 1 correspondingto the depth of the deflection. Details of this will be described later.In short, the characteristic is as follows: the upper surface of thesubstrate 2 for vapor deposition is pressed along the vertical line atthe center of the deflection; the pressed amount is pressed until thelength of the substrate 2 for vapor deposition becomes substantiallyidentical to that of the deposition mask 1 in a bowed state; and thespherical surface of the end portion of the pressing tool 30 which abutsagainst the substrate 2 for vapor deposition preferably has a radius ofcurvature identical to that determined from the curved surface of thedeposition mask 1 in the bowed state.

Here, as each of the lengths of the deposition mask 1 and the substrate2 for vapor deposition, one directional length of a cross section takenalong a line that is parallel to a side of the deposition mask 1 andthat passes through the center of the deflection of the deposition mask1 is considered. The cross section of each of the deposition mask 1 andthe substrate 2 for vapor deposition has a curved surface when they arebowed down. As illustrated in FIGS. 2A and 2B, the length of each curvedsurface can be approximately expressed as the sum of the lengths of thetwo equal sides of an isosceles triangle (only its half is illustratedin FIG. 2B) created by connecting the points A and B: the point A is apoint at which the deposition mask 1 is maximally bowed down; and thepoint B is a point (fulcrum) at which the deposition mask 1 is not boweddown. Considering the half of the isosceles triangle, or a righttriangle OAB, a length AB (L₁ in FIG. 2B) of the hypotenuse can bedetermined from a half (OB in FIG. 2A) of a design length L₀ in anon-bowed state and a maximum value OA (d₀) of the deflection. A radiusr of curvature of the deposition mask 1 in a bowed state is determinedby calculating a length r of a line segment FA. This is because, asillustrated FIG. 2C, if a cross section of the deflection is regarded ashaving an arc shape, an intersection F between a bisector (center is apoint G) of a line segment AB and an extended line passing throughdeflection OA is a central point of a curved line.

The downward amount do (see FIG. 2A) of the deflection of the depositionmask 1 (a distance by which the central portion of the deposition mask 1is bowed downward) relative to the fulcrum on the periphery can bemeasured in an optical manner. When the deposition mask 1 is bowed down,the length of the deposition mask 1 is approximately expressed as 2L₁(see FIG. 2B). In this case,L ₁ =[d ₀ ²+(L ₀/2)²]^(1/2)  (1).If the deposition mask 1 is simply bowed down at the fulcrum on theperiphery, as illustrated in FIG. 2A, the substrate 2 for vapordeposition is pressed by an amount corresponding to the amount ofdeflection d₀ of the deposition mask 1. In this way, the length of thedeposition mask 1 being bowed down becomes substantially identical tothat of the substrate 2 for vapor deposition being pressed. It should benoted that FIG. 1A illustrates the deflection in an exaggerated manner,and an actual amount of deflection d₀ is about 100 μm when thedeposition mask has a size of 700 mm×450 mm, for example.

Referring to FIG. 2C, the midpoint of the line segment AB is denoted byG, a central point of the spherical shape is denoted by F when the bowedshape is regarded as a spherical shape, and FA=r, AB=L₁, and OA=d₀because ΔAGF is analogous to ΔAOB. In this case, the radius r ofcurvature at the center of the deflection is expressed as:r/(L ₁/2)=L ₁ /d ₀r=L ₁ ²/(2d ₀)  (2),where L₁ is determined by equation (1). However, if the thermalexpansion of the deposition mask 1 and the active regions 14 (see FIG.3A) that will be described later are considered, the values L₁ and d₀are changed. In general, the depth of deflection becomes a length d.Therefore, when the amount of deflection illustrated in FIG. 1B is d asdescribed later, Li is also changed as described later. However, thesurface of the pressing tool 30 which abuts against the substrate 2 forvapor deposition is preferably a spherical surface having the radius rof curvature which is determined by d and L₁.

During the vapor deposition, the vapor deposition source 5 vaporizes thevapor deposition material, which then is deposited on the substrate 2for vapor deposition, as described above. In this case, the vapordeposition source 5 has high temperature, and thus the temperature ofthe deposition mask 1 rises. In proportion to this temperature rise, theamount of deflection of the deposition mask 1 increases. Since thedeposition mask 1 is bowed down only during the vapor deposition, theamount of deflection caused due to the thermal expansion is difficult todirectly measure. However, if a linear expansion coefficient andtemperature rise of the deposition mask 1 is denoted by α and t,respectively, for example, an amount of the thermal expansion of thedeposition mask 1 is expressed as αtL₁. As described above, ahalf-length of the bowed deposition mask 1 disposed in the horizontalposition is expressed by L₁. Thus, a half-length L₂ of the depositionmask 1 which reflects its thermal expansion is expressed as:L ₂ =L ₁ +αtL ₁ =[d ₀ ²+(L ₀/2)²]^(1/2) +αtL ₁  (3).In this case, an amount of deflection d₂ of the deposition mask 1 isexpressed as:d ₂=[(L ₁ +αtL ₁)²−(L ₀/2)²]^(1/2).This means that the pressing device 3 presses the substrate 2 for vapordeposition by the amount of deflection d₂, thereby making it possible tocompensate for the thermal expansion of the deposition mask 1 in thefuture. In this case, when the pressing device 3 presses the substrate 2for vapor deposition by the amount of deflection d₂ before thetemperature rises, the deposition mask 1 is pressed and deformed(expanded). As a result, the deposition mask 1 is deformed by thisamount of deflection d₂. Thereafter, when the deposition mask 1 isexpanded due to the temperature rise, its thermal expansion cancels thedeformation of the deposition mask 1. In short, when the thermalexpansion of the deposition mask 1 matches the pressed amount d₂ for thesubstrate 2 for vapor deposition, the substrate 2 for vapor depositionmakes contact with the deposition mask 1. When the temperature rises byabout 1° C. during the vapor deposition, the deposition mask 1 isexpanded by only less than 1 μm due to its coefficient of thermalexpansion. However, when the temperature rise is significant, the effectof the amount of deflection d₂ becomes prominent. When the pressedamount d₂ matches the thermal expansion of the deposition mask 1, thesubstrate 2 for vapor deposition makes contact with the deposition mask1.

In the above example, the deposition mask 1 has an even and uniformoverall body. However, for example, the deposition mask 1 may be amultiple-panel mask for use in performing, at one time, vapor depositionon a plurality of relatively small panels such as smartphones or otherelectric devices. In this case, as in an example illustrated in the planview of FIG. 3A, the deposition mask 1 includes: active regions 14formed within openings in a metal film 13; and fine opening portionsthat are formed in the active regions 14 and correspond to vapordeposition patterns. Each active region 14 may be formed of a resin filmon its overall surface or may be used with a complex mask that includesa resin film and a metal support layer. In any case, since the openingportions are formed in the active regions 14, the active regions 14 havelower rigidness than the portion of the metal film 13 and are bowed downmore easily than that portion. Consequently, as can be seen from FIG. 3Bthat exaggeratedly illustrates a cross section of the deposition mask 1which is taken so as to pass through a center of the deflection of thedeposition mask 1 and parallel to its one side, the present inventorshave found that not only the deflection d₀ of the entire deposition mask1 (at the fulcrum of the periphery) but also deflection h₀ (see FIG. 3C)of each active region 14 is present. Furthermore, the present inventorshave found that it is difficult to bring the substrate 2 for vapordeposition into contact with the deposition mask 1 unless the substrate2 for vapor deposition is expanded in accordance with a varying lengthof the deposition mask 1 which is caused by the deflection h₀ of eachactive region 14.

Next, a description will be given of a method for reducing an influenceof the deflection of the active regions 14. FIG. 3C schematicallyillustrates a cross section of an active region 14 taken along a linethat is parallel to one side of the deposition mask 1 and that passesthrough the center of deflection of the active region 14. In thisexample, similar to the above, a half-length s₁ of the active region 14in a bowed state can be approximately expressed by the length of thehypotenuse of a right triangle PQR. The deflection h₀ of the activeregion 14 can be known through actual measurement. When a length of theabove cross section of the active region 14 is denoted by s₀, thehalf-length s₁ of the active region 14 in the bowed state is expressedas:s ₁ =[h ₀ ²+(s ₀/2)²]^(1/2.)In this case, a variation Δs in the length of the active region 14 isexpressed as:Δs=2(s ₁ −s ₀/2)=2[h ₀ ²+(s ₀/2)²]^(1/2) −s ₀  (4).To cancel the variation in the length of the active region 14, twomethods for pressing the substrate for vapor deposition are conceivable.

In the first method, as illustrated in FIG. 3D, the deposition mask 1 isexpanded until its curved surface becomes smooth. Then, the substrate 2for vapor deposition is pressed at its center until it has the samecurved surface. In this way, the entire surfaces of the substrate 2 forvapor deposition and the deposition mask 1 make contact with each other.In this method, a length L₃ of the hypotenuse of an approximate righttriangle OCD illustrated in FIG. 3E, namely, a length of the depositionmask 1 which reflects the variation Δs in the length of the activeregions 14 is determined. A pressed amount d₁ for the substrate 2 forvapor deposition thereby can be obtained. In FIGS. 3D and 3E, the lengthL₃ of the arc which reflects the deflection of the deposition mask 1 isapproximately expressed by the length of the hypotenuse of the triangleOCD. The pressed shape of the substrate 2 for vapor deposition can alsobe approximately expressed by a triangle O′C′D′, because the pressedshape of the substrate 2 for vapor deposition also substantiallycoincides with that of the deposition mask 1. For this reason, thepressed amount d₁ for the substrate 2 for vapor deposition is identicalto a depth d₁ (length of the line OC) of the deposition mask 1 boweddown at the fulcrum on the periphery, the depth di reflecting thedeflection of the active regions 14.

The length L₃ of the deposition mask 1 is identical to a length to whichthe variations Δs in the lengths of the active regions 14 due to thedeflection are added. Accordingly, the length L₃ is obtained by summingthe variations Δs in the lengths of active regions 14 by a number oftimes that is equal to the number of active regions 14 along the crosssection. Here, an n number of active regions 14 are expected to bepresent along the cross section. When a half portion of the depositionmask 1, as illustrated in FIG. 3E, is considered, the number of activeregions 14 is n/2. Since a variation in the length of the depositionmask 1 per active region 14 is Δs as described above, the length L₃ ofthe hypotenuse in FIG. 3E is expressed as:L ₃ =L ₁+(n/2)Δs  (5).In this case, the length L₁ can be determined from equation (1). FromFIG. 3E, thus, the pressed amount d₁ for the substrate 2 for vapordeposition is expressed as:d ₁ =[L ₃ ²−(L ₀/2)²]^(1/2).In short, to bring the substrate 2 for vapor deposition into contactwith the deposition mask 1, the upper surface of the substrate 2 forvapor deposition needs to be pressed, by an amount corresponding to thelength d₁, along a vertical line at the center of the deflection of thedeposition mask 1 relative to the fulcrum on its periphery. It should benoted that the above explanation does not consider the influence of thethermal expansion. When the thermal expansion is considered, the lengthL₂ determined from equation (3) may be used in equation (5), instead ofthe length L₁.

In the second method, as illustrated in the schematic view of FIG. 4A,the upper surface of the substrate 2 for vapor deposition is pressedalong vertical lines at the centers of the deflection of the respectiveactive regions 14, whereby the substrate 2 for vapor deposition isbrought into contact with the deposition mask 1 at the active regions14. One concept in this case is that the substrate 2 for vapordeposition is bowed down in accordance with the deflection of the activeregions 14 in the deposition mask 1. Consider a pressed amount d₃ foreach active region 14 in this case. As can be seen from a proximateright triangle illustrated in FIG. 4B which is similar to the aboveright triangles, for example, the substrate 2 for vapor deposition needsto be pressed by the pressed amount d₀ at the center of the deflectionof the deposition mask 1 relative to the fulcrum on the periphery.Therefore, to bring the deposition mask 1 into contact with thesubstrate 2 for vapor deposition, an active region 14 x that is adistance x away from the periphery (edge fixed to the frame 12) needs tobe pressed by an amount corresponding to the sum of x/(L₀/2) times theamount of deflection d₀ of the entire deposition mask 1 as described inFIG. 4B, that is 2d₀x/L₀, and the amount of deflection h₀ of an activeregion 14. The pressed amount d₃(x) is expressed as:d ₃(x)=2d ₀ x/L ₀ +h ₀.

In the above case, a depth d_(x) of the deflection of the active region14 x is determined by modifying the depth do of the deflection of theentire deposition mask 1 relative to the fulcrum on the periphery inproportion as the position of the active region 14 x. Under thecondition of all the active regions 14 being bowed down to the samedegree, the deflection of each active region 14 is denoted by h₀. If thesubstrate 2 for vapor deposition is made of a material having highrigidness, such as glass, the pressed amount for an active region may beinfluenced by pressing of a next active region. Therefore, each activeregion 14 needs to be pressed while an actual pressed amount is measuredand adjusted to a target amount. However, if the substrate 2 for vapordeposition is a thin glass plate or flexible substrate that does nothave high rigidness or if the active regions 14 are arranged atconsiderably long intervals, an active region 14 may not be greatlyinfluenced by the pressing of a next active region 14, and thus eachactive region 14 may be pressed by a preset pressed amount. In FIG. 4A,the arrow lines above the substrate 2 for vapor deposition indicatepositions at which loads are applied in order to press the substrate 2for vapor deposition.

Since the active regions need to be pressed at different forces in theabove case, different pressing members, each of which has a plunger, anactuator, and some other parts, preferably press these active regionsindependently of one another. Each plunger preferably has a round endwith a curved surface, as described above. If having a sharp end, eachplunger preferably may tear the substrate 2 for vapor depositionespecially when the substrate 2 for vapor deposition is a flexiblesubstrate, or each plunger preferably may damage the substrate 2 forvapor deposition when the substrate 2 for vapor deposition is made ofglass. In this case, similar to the above example, the end of eachplunger preferably has a spherical surface according to a radius ofcurvature of deflection of a corresponding active region 14. Moreover,the pressing tools 30 (see FIG. 4C) that has an overall sphericalsurface are preferably used.

When the above pressing tool 30 abuts against the substrate 2 for vapordeposition so as to make contact with its wide area, the spherical cap33 with projection may be used as an example of the pressing tool 30. Asillustrated in FIG. 4C, the spherical cap 33 with projection has asurface of spherical cap 33 b and projection parts 33 c. The surface ofspherical cap 33 b is formed so as to swell largely at the center of thedeflection of the deposition mask 1 relative to the fulcrum on theperiphery but to swell less largely at the periphery of the depositionmask 1. Each projection part 33 c is formed in relation to thedeflection of a corresponding active region 14 at its position. Usingthe spherical cap 33 with projection can completely bring the substrate2 for vapor deposition into contact with the deposition mask 1especially when the substrate 2 for vapor deposition is a flexiblesubstrate. In this case, a radius of curvature of the surface ofspherical cap 33 b is determined using the radius r defined by equation(2) and the length L₂ reflecting the thermal expansion. A radius ofcurvature of each projection part 33 c is calculated from FIG. 3C in amanner similar to the above way in FIG. 2C. Although the projection part33 c is also illustrated in this case, the surface of spherical cap 33 bthat does not have the projection part 33 c may be integrated with orbonded to the touch plate 41 (see FIG. 1B).

As illustrated in FIG. 1A, for example, the vapor deposition apparatusof the present invention includes a mask holder 15, a substrate holder29, the touch plate 41, the vapor deposition source 5, and the pressingdevice 3. The mask holder 15 allows the deposition mask 1 to be disposedthereon. The substrate holder 29 is provided so as to be able to holdthe substrate 2 for vapor deposition. The touch plate 41 is provided onthe substrate 2 for vapor deposition held by the substrate holder 29while being in contact with the periphery of the substrate 2 for vapordeposition. The vapor deposition source 5 is provided on an oppositeside of the substrate holder 29 to the deposition mask 1 mounted on themask holder 15. The vapor deposition source 5 vaporizes the vapordeposition material. The pressing device 3 presses the upper surface ofthe substrate 2 for vapor deposition. The pressing device 3 is providedso as to be able to press the upper surface of the substrate 2 for vapordeposition, held by the substrate holder 29, along a vertical line atthe center of the deflection of the deposition mask 1 (e.g., thedeflection of the entire deposition mask 1 or deflection of theindividual active regions 14). In the example illustrated in FIG. 1A,the pressing device 3 presses the pressing tool 30 against the substrate2 for vapor deposition by using the touch plate 41; however, thisexample is not limitative. Other examples will be described later.

As described above, the pressing device 3 may be formed so as to pressthe substrate 2 for vapor deposition by an amount of do or more and d₂or less, or by the amount d₃(x).

As illustrated in FIGS. 1A and 1B that have been referenced, thepressing device 3 may include the pressing tool 30 and a pressingmember. The pressing tool 30 may a rigid body, for example, made of ametal or plastic having high rigidness; the pressing member may includethe touch plate 41 and the actuator. Although not illustrated, variouspressing devices, such as a plunger and an actuator, may be used. Inshort, the pressing device 3 is characterized in that it is formed so asto press the center of deflection of any part by a predetermined amount.It is more preferable that the pressing device 3 is configured to abutagainst not only the center but also its surrounding area, including theperiphery of the substrate 2 for vapor deposition.

FIGS. 1B and 4C illustrate examples of the above configuration.Referring to the example in FIG. 1B, the spherical cap 32 is disposedbetween the touch plate 41 and the substrate 2 for vapor deposition; thespherical cap 32 conforms to a shape of the deflection of the depositionmask 1 at the fulcrum on the periphery, similar to the structure in FIG.1A. Aside from the shape of the pressing tool 30, the structure in FIG.1B is identical to that in FIG. 1A. Therefore, the same referencenumerals are given to the identical components and they will not bedescribed. In this example, the spherical cap 32 is formed such that itsportion (base section 32 a) is embedded in the touch plate 41. However,the spherical cap 32 does not necessarily have to be embedded in thetouch plate 41. Alternatively, the spherical cap 32 may be integratedwith the touch plate 41. The spherical cap 32 only has projection partsfrom the touch plate 41 by a predetermined amount d. In this example,the spherical cap 32 needs to press the center of the deflection of thedeposition mask by the predetermined amount d.

It is considered that, the substrate 2 for vapor deposition is broughtinto contact with the deposition mask in accordance with the idea inFIG. 4A. By using the spherical cap 33 with projection as the pressingtool 30, the substrate 2 for vapor deposition can be brought intocontact with the deposition mask 1. In the spherical cap 33 withprojection, as illustrated in FIG. 4C, the projection parts 33 c areformed on the surface of spherical cap 33 b. Each projection part 33 chas an arc-shaped cross section with a radius of curvature according tothe deflection of a corresponding active region 14. The surface ofspherical cap 33 b has a radius of curvature r (r is a radius defined byequation (2) or a radius in which a length caused by the thermalexpansion is added into the radius of equation (2)) in a case where thedeflection d₀ of the deposition mask 1 occurs at the fulcrum on theperiphery. In this case, as described above, the radius of curvature ofthe spherical surface of the projection parts 33 c in each active region14 is determined from FIG. 3C.

The substrate holder 29 holds the peripheral edge of the substrate 2 forvapor deposition with a plurality of hook-shaped arms and is connectedto an unillustrated driving device so as to be capable of ascending anddescending vertically. The substrate 2 for vapor deposition carried intothe vapor deposition apparatus by robot arms, is received by thehook-shaped arms, and the substrate holder 29 is lowered until thesubstrate 2 for vapor deposition is in proximity to the deposition mask1. In addition, an unillustrated image device is provided for performingalignment. The touch plate 41 is supported by a support frame 42. In theexample illustrated in FIG. 1A, the support frame 42 lowers until thetouch plate 41 makes contact with and presses the periphery of thesubstrate 2 for vapor deposition with the sphere (pressing tool) 31therebetween. In this way, the substrate 2 for vapor deposition isbrought into contact with the deposition mask 1. An unillustratedpressing member such as an actuator is also provided. The touch plate41, which is basically provided to make the substrate 2 for vapordeposition flat, may be made of a plate material having high rigidness.Therefore, the touch plate 41 is less likely to be deformed even whenpressing the pressing tool 30, that is the sphere 31 such as a steelball as illustrated in FIG. 1A. The touch plate 41 descends verticallywhile pressing the pressing tool 30, and makes contact with theperiphery of the substrate 2 for vapor deposition, thereby deforming thesubstrate 2 for vapor deposition.

The sphere 31 has a height corresponding to the distance between thetouch plate 41 and the substrate 2 for vapor deposition to the pressedamount d. In the example illustrated in FIG. 1A, the sphere 31 isconfigured to be partly embedded in the touch plate 41. Further, thesphere 31 is formed such that its diameter is greater than thepredetermined length d and it is exposed from the touch plate 41 by thepredetermined length d. This structure enables the sphere 31 to moveonly vertically in relation to the vertical movement of the touch plate41 without having to move horizontally. As a result, the deflection ofthe substrate 2 for vapor deposition coincides with that of thedeposition mask 1, so that they make contact with each other. However,the configuration of the pressing device 3 is not limited to this.Alternatively, the pressing device 3 may be configured to lower aplunger with an actuator to press the substrate 2 for vapor deposition.In this case, it is preferable that the touch plate 41 has athrough-hole and that the plunger pass through this through-hole andpress the substrate 2 for vapor deposition. The touch plate 41 has highrigidness as described above. If the substrate 2 for vapor deposition ispressed by the flat surface of the touch plate 41, the pressure isdistributed across the substrate 2 for vapor deposition. In which case,it may be difficult to press the center of the deflection of thesubstrate 2 for vapor deposition. It is necessary to press the center ofthe deflection of the substrate 2 for vapor deposition.

Unillustrated cooling water may circulate inside the touch plate 41,allowing the touch plate 41 to realize a function of cooling both thesubstrate 2 for vapor deposition and the deposition mask 1. The pressingtool 30 is not limited the pressing device 3 showed in FIG. 1A. Asurface of the touch plate 41 which abuts against the substrate 2 forvapor deposition is formed into a shape the same as that of a surface ofthe pressing tool 30 which would abut against the substrate 2 for vapordeposition and also formed so as to have a curved surface with theheight of the predetermined length d as shown in the above example.

Before the substrate 2 for vapor deposition is pressed, the substrate 2for vapor deposition and the deposition mask 1 are aligned with eachother. During the alignment, the substrate 2 for vapor deposition ismoved relative to the deposition mask 1 while alignment marks formed,respectively, on the deposition mask 1 and the substrate 2 for vapordeposition are being imaged. Thus, the vapor deposition apparatusfurther includes: an unillustrated image device that images thealignment marks; and an unillustrated fine movement device that finelymoves the substrate 2 for vapor deposition. Furthermore, all thecomponents in FIG. 1A are placed in an unillustrated chamber, and avacuum apparatus is provided to make an inside of the chamber vacuum.

As the deposition mask 1 may be used various types of deposition masks,examples of which include: a mask with a resin film alone; a complexmask in which a resin film and a metal support layer are laminated; amultiple-panel mask for use in forming a plurality of panels at onetime; and metal masks.

If a resin film is used in the deposition mask 1, the resin film 11preferably has a linear expansion coefficient similar to that of thesubstrate 2 for vapor deposition; however, there is no specificlimitation on a material of the resin film 11. Examples of the materialof the resin film 11 include a polyimide (PI) resin, polyethylenenaphthalate (PEN) resin, polyethylene terephthalate (PET) resin,cycloolefin polymer (COP) resin, cyclic olefin copolymer (COC) resin,polycarbonate (PC) resin, polyamide resin, polyamide-imide resin,polyester resin, polyethylene resin, polyvinyl alcohol resin,polypropylene resin, polystyrene resin, polyacrylonitrile resin,ethylene vinylacetate copolymer resin, ethylene-vinyl alcohol copolymerresin, ethylene-methacrylic acid copolymer resin, polyvinyl chlorideresin, polyvinylidene chloride resin, cellophane, and ionomer resin. Thepolyimide resin is especially preferred, because its linear expansioncoefficient can be adjusted in accordance with a condition such as aprofile of a temperature rise in the heat treatment if the resin film isformed by applying a precursor solution and by subjecting the precursorsolution to a heat treatment. However, the material of the resin film 11is not limited to the polyimide resin. The resin film 11 may have athickness of approximately several to several tens of micrometers, forexample, 5 μm or more, 10 μm or less.

When the metal support layer is formed using a magnetic material, anunillustrated magnet can be provided over the opposite side of thesubstrate (for vapor deposition) 2 to the deposition mask 1 tomagnetically attract and fix the metal support layer. However, thisconfiguration is not limitative. If this metal support layer isprovided, openings that are slightly larger in size than that of theopening portions formed in the resin film are formed in the metalsupport layer. This metal support layer may be formed such that itsthickness falls in 5 μm or more and 30 μm or less. If the depositionmask 1 is a multiple-panel mask, the active regions 14 are formed withinthe deposition mask 1 in relation to panels in the metal layer 13, forexample, as illustrated in FIG. 3A. Each active region 14 is formed of aresin film alone. In each active region 14, an opening portion may beformed, or the metal support layer may be formed around this openingportion 3. The metal support layer and the metal layer may be identicalmaterial to each other, or the active regions 14 formed independentlymay be bonded to the opening portions of the metal layer 13. The metallayer 13 preferably has a linear expansion coefficient similar to thatof the substrate 2 for vapor deposition. Invar (alloy of Fe and Ni) isespecially preferred because it is not greatly thermally expanded.

The deposition mask 1 has been enlarged year by year, and the size ofits one side has exceeded one meter. In addition, the resin film, themetal support layer, and the metal layer 13 are all formed of anextremely thin film. Therefore, when the deposition mask 1 is disposedin a horizontal position with its periphery fixed by the frame 12, asillustrated in FIG. 1A, the deposition mask 1 may be bowed down somedegree. To prevent this deflection, a tension is applied to a maskmaterial in all directions (so that the mask material is expanded)before mask materials such as the resin film are bonded to the frame,and then the mask material is bonded to the frame 12. Nevertheless, whensuch extremely thin film is held in a horizontal positon while bonded toa large frame body (frame 12) whose size exceeds one meter, they may bebowed down. This deflection is very difficult to prevent. As describedabove, the present invention subjects the substrate 2 for vapordeposition to conform to the deflection of the deposition mask 1.However, various problems are still present. For example, the depositionmask 1 may be bowed down due to not only its weight but also its thermalexpansion. If a multiple-panel deposition mask, as described above, orother similar mask in which both the metal layer 13 and the activeregion 14 are formed is used, especially its active regions 14 in thismask may be bowed down due to a difference in rigidness between theirmaterials. As a result, the present inventors have found that simplypressing the substrate 2 for vapor deposition by an amount correspondingto the amount of deflection of the deposition mask 1 does not alwaysbecome a solution. Further, the present inventors have also found that,in the light of various deflection mechanisms of the deposition mask 1,it is possible to bring the substrate 2 for vapor deposition intocontact with the deposition mask 1 by pressing the substrate 2 for vapordeposition along a central axis of the deflection of the deposition mask1.

The frame 12 is usually made of a material, such as invar, that is notgreatly thermally expanded. In addition, the frame 12 resists deflectionand high temperatures, because it has a relatively large thickness, forexample, ranging from about 25 mm or more and 50 mm or less, as opposedto a thin film such as the resin film or the metal support layer.Therefore, the deflection mainly occurs in portions of the resin filmand the metal support layer (metal layer 13). The deposition mask 1 isbowed down in a curved shape, namely, in a substantially arc shape. Ifthe substrate 2 for vapor deposition is used in an organic EL displayapparatus, it is made of a glass substrate or a flexible substrate madeof a resin film, for example. If glass is used, the substrate 2 forvapor deposition is less likely to be deformed spot like, and likely tobe bowed down in a curved shape even when pressed at a single point.Thus, when the upper surface of the substrate 2 for vapor deposition ispressed at a position immediately above the center of the deflection ofthe deposition mask 1, the substrate 2 for vapor deposition can beoverlaid easily on the deposition mask 1 being bowed down. To determinethe depth of the deflection, as described above, an actual length of(the curved surface of) the deposition mask 1 is approximately expressedby a length of the hypotenuse of a right triangle. Moreover since thesubstrate 2 for vapor deposition has a similar shape, its error is verysmall. If the substrate 2 for vapor deposition is a flexible substrate,when a shape of a pressed portion of the substrate 2 for vapordeposition is similar to an arc shape of the deposition mask 1, thesubstrate 2 for vapor deposition can be formed easily into a similarcurved shape. Consequently, when the deposition mask 1 is bowed down atthe fulcrum on its periphery due to its weight, the substrate 2 forvapor deposition can easily be brought into contact with the depositionmask 1 with the contact surfaces formed into the same curved shape bypressing the substrate 2 for vapor deposition, by an amountcorresponding to the amount of deflection d₀ of the deposition mask 1 asdescribed in FIG. 2A, at a position that is vertical at the center ofthe deflection of the deposition mask 1 and that is on the upper surfaceof the substrate 2 for vapor deposition as illustrated in FIG. 1A.

The vapor deposition source 5 may be any given vapor deposition sourcehaving a point, line, or plane shape. For example, the vapor depositionsource 5 of the linear type (extends in a direction perpendicular to thepage of FIG. 1A) in which crucibles are arrayed, so called a linearsource, is moved from the left edge to right edge of the page. Theentire surface of the substrate 2 for vapor deposition is therebydeposited. As described above, the vapor deposition source 5 emits thevapor deposition material as an emitted beam. A cross section of thisemitted beam has a fan shape defined by a shape of the crucibles, andboth sides of the cross section have a certain angle. To deliver, at apredetermined site of the substrate 2 for vapor deposition, particles ofthe vapor deposition material in the vapor deposition beam even near itsedge which has the fan-shape cross section without being blocked by thedeposition mask 1, area of the deposition mask 1 near the openingportion are each formed into a tapered shape. Alternatively, however,the openings 12 a in the metal support layer 12 may also have a large,non-tapered shape.

Next, a method for manufacturing an organic EL display apparatus usingthe vapor deposition method of the present invention will be described.Any processes in the manufacturing method other than the vapordeposition method can be performed by the well-known methods. Thus, amethod for depositing organic layers by the vapor deposition method ofthe present invention will be mainly described with reference to FIGS.5A and 5B.

The method for manufacturing an organic EL display apparatus of thepresent invention includes: forming a device substrate 21 by formingTFTs (not illustrated), a planarizing layer, and first electrodes (forexample, anodes) 22 on a support substrate (not illustrated); overlayingand aligning the deposition mask 1 manufactured with the above method onthe device substrate 21; and forming a deposition layer 25 of organiclayers by depositing the organic material 51. Then, a second electrode26 (cathode) is formed on the deposition layer 25.

The device substrate 21 is formed by a process described below. Forexample, although not illustrated, switching elements, such as TFTs, areformed on a support substrate, such as a glass plate, in units of RGBsub-pixels in each pixel, and the first electrodes 22 connected to theswitching elements are formed, on the planarizing layer, by acombination of a metal layer made of Ag or APC or the like, for example,and an ITO layer. As illustrated in FIGS. 5A and 5B, insulating bank 23made of SiO₂, an acrylic resin, a polyimide resin, for example, areformed between the sub-pixels to divide the sub-pixels from each other.The above-mentioned deposition mask 1 is aligned with and fixed on theinsulating banks 23 on the device substrate 21. As described above, thefixing is typically performed, for example, by using electromagnet 3,which is provided over the surface opposite to the vapor depositionsurface of the device substrate 21, to attract the deposition mask 1. Inthe present invention, however, it is unnecessary to attract thedeposition mask 1, in other words, to use a so-called a magnetic chuck.Since the touch play 41 presses the device substrate 21, the devicesubstrate 21 brings into contact with the deposition mask 1 and theinsulating banks 23 in the device substrate 21 is fixed with thedeposition mask 1.

In the above state, as illustrated in FIG. 5A, the organic material 51is evaporated from the vapor deposition source (crucibles) 5 in thevapor deposition apparatus, and then the organic material 51 isdeposited only on parts of the device substrate 21 corresponding toparts of the deposition mask 1 in which the opening portions 11 a areformed, so that the deposition layer 25 of the organic layers is formedon the first electrodes 22 in desired sub-pixels. Since the openingportion 11 a in the deposition mask 1 is formed such that the diameteris shorter than the gap between opposed walls each other of theinsulating banks 23, as described above, the organic material 51 is lesslikely to be deposited on the side wall of the insulating banks 23. As aresult, as illustrated in FIGS. 5A and 5B, the deposition layer 25 ofthe organic layers is basically deposited only on the first electrodes22. This vapor deposition step may be performed on each sub-pixel bysequentially replacing one deposition mask 1 with another. A depositionmask may be used to deposit the same material on a plurality ofsub-pixels at the same time. According to the present invention, thedeposited layer 25 of the organic layers can be formed with greatprecision, because the deposition mask 1 is in contact with theinsulating banks 23 on the device substrate 21.

FIGS. 5A and 5B each simply illustrate the deposition layer 25 of theorganic layers by a single layer, but in fact the deposition layer 25 ofthe organic layers may be formed of the deposition layers 25 of aplurality of layers made of different materials. For example, a holeinjection layer is provided as a layer in contact with the anode 22 insome cases. The hole injection layer improves a hole injection propertyand is made of material having a good ionization energy matching. A holetransport layer is formed of, for example, an amine-based material onthe hole injection layer. The hole transport layer improves stabletransportability of holes and enables confinement of electrons (energybarrier) into a light emitting layer. Further, the light emitting layer,which is selected depending on a target emission wavelength, is formedon the hole transport layer, for example, by doping red or green organicphosphor material into Alq₃, for the red or green wavelength. As ablue-type material, a bis(styryl)amine (DSA)-based organic material isused. An electron transport layer is formed of Alq₃, for example, on thelight emitting layer. The electron transport layer improves an electroninjection property and stably transports electrons. These respectivelayers, each having a thickness of approximately several tens ofnanometers, are deposited to form the deposition layer 25 of the organiclayers. It should be noted that an electron injection layer, such as LiFor Liq, which improves the electron injection property, may also beprovided between the organic layers and the metal electrode.

In the deposition layer 25 of the organic layers, an organic layer of amaterial corresponding to each color of RGB is deposited as the lightemitting layer. In addition, the hole transport layer, the electrontransport layer, and other similar layers are preferably depositedseparately by using materials suitable for the light emitting layer, ifemphasis is placed on light emission performance. However, inconsideration of the material cost, the same material common to two orthree colors of RGB may be deposited in some cases. In a case where thematerial common to sub-pixels of two or more colors is deposited, thedeposition mask 1 is formed to have opening portions 11 a formed in thesub-pixels sharing the common material. In a case where individualsub-pixels have different deposited layers, for example, one depositionmask 1 is used for sub-pixels of R, so that the respective organiclayers can be sequentially deposited. In a case where an organic layercommon to RGB is deposited, other organic layers for the respectivesub-pixels are deposited up to the lower side of the common layer, andthen at the stage of the common organic layer, the common organic layeris deposited across the entire pixels at one time using the depositionmask 1 with the opening portions 11 a formed at RGB sites.

After finishing the formation of the deposition layer 25 of all theorganic layers and the electron injection layer, such as a LiF layer,the deposition mask 1 is separated, and the second electrode (e.g.,cathode) 26 is formed over the entire surface. An example illustrated inFIG. 5B is a top emission type, in which light is emitted from a surfaceopposite to the device substrate 21 illustrated in the figure. Thus, thesecond electrode 26 may be formed of a light-transmissive material, forexample, a thin Mg—Ag eutectic layer. Alternatively, for example, Al maybe used. It should be noted that in a bottom emission type which emitslight through the device substrate 21, ITO or In₃O₄, for example, may beused for the first electrodes 22, and metals having low work functions,for example, Mg, K, Li, or Al may be used for the second electrode 26. Aprotective layer 27 made of, for example, Si₃N₄, is formed on a surfaceof the second electrode 26. It should be noted that the whole depositedlayers are sealed with a sealing layer made of glass or amoisture-resistant resin film (not illustrated), for example, and isthus configured to prevent the deposition layer 25 of the organic layersfrom absorbing moisture. Alternatively, a structure can also be providedin which the organic layers may be made common or shared as much aspossible, and a color filter may be provided on the surface side of theorganic layers. The deposition mask 1 configured above is reusable.

REFERENCE SIGNS LIST

-   1 Deposition mask-   2 Substrate for vapor deposition-   3 Pressing device-   5 Vapor deposition source-   12 Frame-   13 Metal layer-   14 Active region-   15 Mask holder-   21 Device substrate-   22 First electrode-   23 Insulating bank-   25 Deposition layer-   26 Second electrode-   27 Protective layer-   29 Substrate holder-   30 Pressing tool-   31 Sphere-   32 Spherical cap-   32 a Base section-   33 Spherical cap with projection-   33 a Base section-   33 b Surface of spherical cap-   33 c Projection-   41 Touch plate-   42 Support frame

The invention claimed is:
 1. A vapor deposition method comprising:disposing a deposition mask having a plurality of active regions in eachof which a pattern of opening portions is to be formed, in a horizontalposition with holding its periphery; mounting a substrate for vapordeposition over an upper surface of the deposition mask so as to beoverlaid on the deposition mask, a vapor deposition layer to be formedon the substrate for vapor deposition; disposing a vapor depositionsource so as to face the deposition mask; and forming the vapordeposition layer on the substrate for vapor deposition by deposing avapor deposition material in the vapor deposition source; wherein thesubstrate for vapor deposition is pressed vertically at a position of acenter of deflection of the deposition mask and on an upper surface ofthe substrate for vapor deposition, by an amount or more obtained byadding sum of amount of deflection of the plurality of active regions toan amount of the deflection of the deposition mask relative to a fulcrumon the periphery of the deposition mask, while depositing by pressingtool.
 2. A vapor deposition method comprising: disposing a depositionmask having a plurality of active regions in each of which a pattern ofopening portions is to be formed, in a horizontal position with holdingits periphery; mounting a substrate for vapor deposition over an uppersurface of the deposition mask so as to be overlaid on the depositionmask, a vapor deposition layer to be formed on the substrate for vapordeposition; disposing a vapor deposition source so as to face thedeposition mask; and forming the vapor deposition layer on the substratefor vapor deposition by deposing a vapor deposition material in thevapor deposition source; wherein the substrate for vapor deposition ispressed vertically at positions that are centers of the respectiveactive regions and that are on the upper surface of the substrate forvapor deposition, by pressed amounts d3(x) (=h0+dx) or more, each of thepressed amounts d3(x) being equivalent to a sum of deflection h0 of acorresponding active region and deflection dx which is a deflection ofthe deposition mask at a center point of one of active regions, the oneof active regions being in a distance x from the fulcrum on theperiphery of the deposition mask, the deflection dx being calculatedproportionally in accordance with the distance x between a position ofthe corresponding active region and the periphery of the depositionmask.
 3. A method for manufacturing an organic EL display apparatus bydepositing organic layers on a device substrate, the method comprising:forming the device substrate by forming at least a TFT and a firstelectrode on a support substrate; forming a deposited layer of theorganic layers on the device substrate by depositing organic materialson the first electrode with the vapor deposition method according toclaim 1; and forming a second electrode on the deposition layer.
 4. Thevapor deposition method according to claim 2, wherein an end of thepressing tool to press by the pressed amounts is formed sphericalsurface corresponding to bowed shape of the active regions.